The invention relates to coating compositions for the anti-adhesive coating of wound dressings, anti-adhesive layers, especially for wound dressings, anti-adhesive coated dressings and methods for manufacture of the coating compositions or anti-adhesive layers.
The purpose of a bandage is to protect the wound from the effects of its surroundings, to absorb the wound fluid and to aid in the healing process. It is known that during the healing process the wound and the bandaging material stick together. During changing of the wound padding, this sticking of wound to bandage can lead to renewed damage to the healing wound. In addition to the pain which a patient, especially one having chronic wounds, has to endure during regular bandage changing, repeated damage to the healing wound also results in an overall delay in the wound healing process. On this basis it is desirable that bandages have low tendency to stick to the wound.
Up until now, methods to produce bandages having low tendency to stick issue mostly from a multilayer bandage material comprising layers of different types of textile (WO99/611077; European Patent 1097682; German Patent 10014557). The textile layer which is immediately adjacent to the wound in these bandages usually consists of a hydrophobic textile or a polymer film, which has only a small tendency to stick to the wound. Behind this contact layer, an absorbent textile material is then applied for absorption of fluid from the wound. In contrast to wound dressings that consist of only one type of textile, such multilayer bandage systems have essentially two disadvantages. For one, they are less convenient to handle, since the wound may be covered exclusively by the contact area of the wound dressing. Another reason is that the manufacture of such multilayer wound dressings is significantly more costly in comparison to single component materials, since two different textile materials must be joined together in an additional operation.
In a new type of multilayer bandage material the surface, which is directly on top of the wound, consists of an elastomeric hydrogel layer, which can have hydrophilic as well as hydrophobic properties (WO00/16725; European Patent 261167). These systems do indeed have a significantly lower tendency to stick to the wound, but are difficult to handle, since firstly only the dressing contact itself may be placed on the wound and additional precautions must be taken so that the hydrogel is not dried out or contaminated. Another disadvantage is that the manufacture of such multilayer bandages with a hydrogel layer is significantly more expensive than the production of bandage systems consisting of only one textile material.
Based on the disadvantages of multilayer bandage systems methods were evolved to develop textile materials having low sticking tendencies and at the same time good water absorption capabilities. One method therein comprises interweaving hydrophobic and hydrophilic strands with each other resulting in a single layer textile wound dressing having lower wound adhesion (European Patent 1106149). Thus, a single layer bandage of a mixed web is provided. It is more favorable, however, if a conventional material is modified in such a manner that it exhibits decreased adhesion to the wound.
Such a method is presented by the hydrophobic modification of cellulose material by means of carboxylation (WO 00/01425). Making cellulose hydrophobic lowers the adhesion of wound dressings to the wound and thereby induces a decreased tendency to stick. However, the disadvantage of this method is that it only permits the modification of cellulose bandages whereas other bandage materials such as, for example, polyamide or viscose can not be improved by carboxylation.
The object of the invention is to provide improved coating compositions for the anti-adhesive preparation of wound dressings, with which the disadvantages of conventional wound dressings are avoided, and methods for their manufacture. In particular, the coating compositions should allow the production of wound dressings having decreased tendency for sticking between the wound and the bandage material. Moreover, the preparation of cost-effective anti-adhesive wound dressings should be made possible. Further, the invention should also be applicable to different bandage materials.
These objects are achieved by means of coating compositions, anti-adhesive layers, wound dressings and methods having the features as described herein.